Finasteride

A type II 5-alpha-reductase inhibitor. Finasteride blocks the enzyme that converts testosterone into DHT, the hormone that miniaturizes your hair follicles and drives pattern loss. Where minoxidil stimulates growth directly, finasteride stops the underlying cause, which is why the standard stack runs both together. At 1 mg daily it cuts DHT hard enough to slow or reverse miniaturization in most men.

The topical version is the newer move: apply finasteride to the scalp, get the local DHT suppression, and keep systemic exposure to a fraction of what the pill delivers. Same mechanism, narrower footprint. If you have no reason to prefer oral, start topical.

The evidence base here is unusually deep, with controlled trials stretching past two decades:

The dose is flat: 1 mg daily, every day, for as long as you want to keep your hair. No titration. Give it six months before judging, because the hair cycle is slow and the regrowth builds invisibly before it shows. Stopping means the DHT comes back and the loss resumes, so think of finasteride as a long commitment, not a course.

Topical finasteride is the route I would start most people on. The phase 3 numbers matched oral numerically while keeping systemic exposure to a fraction of the pill. If the sexual side-effect risk is your concern, topical is the direct answer.

If finasteride is not enough after a full year, dutasteride is the next step: deeper DHT suppression for more aggressive loss.

The standard pair is finasteride plus minoxidil: one stops the loss, the other pushes regrowth. Add ketoconazole shampoo a few times a week for a clean scalp and a mild anti-androgen bonus, and you have the proven triple stack.

The safety profile is well mapped after decades and millions of prescriptions: